The proposed research project is part of a continued effort to understand the molecular mechanism underlying electrical excitability. I postulate that ionic pathways responsible for electrical excitability in cell membranes open and close when molecular channel subunits assemble and disassemble as a function of the electric field across the membrane. The theoretical analysis of the concept of a subunit channel of electrical gating reveals that it can account for such steady-state and kinetic features of gating systems as negative slope resistance, steep conductance-voltage relation, delay, inactivation, state-dependent kinetic features, gating current, and single channel conductance phenomena. I intend to test the postulated molecular mechanism by devising experiments that will a) distinguish the hypothesis from others and b) test the self-consistency of the hypothesis. In a collaborative effort these experiments will be carried out on excitable cell membranes using conventional voltage-clamp techniques in conjunction with advanced kinetic relaxation methods. The experimental data will be evaluated in the context of the subunit channel concept and control models. The immediate goal is to work out a simple unified molecular conceptual framework for both cell and model membrane excitability while the long-term goal is to formulate the basis for a general theory of electrical excitability in membranes.